Machine for forming a continuous seamless concrete pipe

ABSTRACT

A continuous seamless pipe is formed in a trench from a cementitious mix by advancing through the trench a carriage mounting a trailing cylindrical drum with its axis parallel to the direction line of carriage movement and a diameter equal to the internal pipe diameter, and a cylindrical skirt having a diameter approximating the outer pipe diameter concentrically surrounding the drum to define an intervening rearwardly opening annular cylindrical containing an annular piston. The cementitious mix is fed into the front end of the cylinder and the piston is driven rearwardly through the cylinder to extrude the mix through the open rear end of the cylinder to form the pipe wall and exert a forward reaction force on the carriage for propelling the latter through the trench. The plunger may be segmented to obtain more uniform extrusion about the full cylinder circumference. The drum may be driven in rotary or other motion, and the drum, plunger and/or skirt may be vibrated to compact the extruding mix. A rotary trowel on the rear end of the drum smooths the inner surface of the extruded pipe. The preferred cementitious mix is a low slump concrete which may be extruded to form a seamless concrete pipe without the need to internally support the pipe.

United States Patent [191 Johnson et al.

[ MACHINE FOR FORMING A CONTINUOUS SEAMLESS CONCRETE PIPE [22] Filed:Jan. 24, 1972 [21] Appl. No.: 220,258

[52] US. Cl. 4125/59, 425/64 [51] Int. Cl K103i 3/06 [58] Field ofSearch 425/59, 63, 64, 62; 264/32, 33

[56] References Cited UNITED STATES PATENTS 2,734,248 2/1956 Gaudin425/64 X 2,406,025 8/1946 Moor 425/59 3,530,552 9/1970 Calder 425/622,520,199 8/1950 Butcher 425/59 3,193,901 7/1965 Lee et a].., 425/593,363,524 l/l968 Cutenacci.... 94/46 3,562,056 2/1971 Olson 264/33 X3,534,449 10/1970 Bllxt et al. 425/62 Primary ExaminerRobert D. BaldwinAssistant ExaminerJohn McQuade Attorney-Boniard I. Brown [451 Jan.15,1974

[57] v ABSTRACT A continuous seamless pipe is formed in a trench from acementitious mix by advancing through the trench a carriage mounting atrailing cylindrical drum with its I axis parallel to the direction lineof carriage movement and a diameter equal to the internal pipe diameter,and a cylindrical skirt having a diameter approximating the outer pipediameter concentrically surrounding the drum to define an interveningrearwardly opening annular cylindrical containing an annular piston Thecementitious mix is fed into the front end of the cylinder and thepiston is driven rearwardly through the cylinder to extrude the mixthrough the open rear end of the cylinder to form the pipe wall andexert a forward reaction force on the carriage for propelling the latterthrough the trench. The plunger may be segmented to obtain more uniformextrusion about the full cylinder circumference. The drum may be drivenin rotary or other motion, and the drum, plunger and/or skirt may bevibrated to compact the extruding mix. A rotary trowel on the rear endof the drum smooths the inner surface of the extruded pipe. Thepreferred cementitious mix is a low slump concrete which may be extrudedto form a seamless concrete pipe without the vneed to internally supportthe pipe.

8 Claims, 7 Drawing Figures o o O /0/ o T o /0 1, a /4 /00-. Z0

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PATENTEDJAN l 5|974 SHEET 2 BF 2 FIG. 4.

FIG. 3.

MACHINE FOR FORMING CONTINUOUS SEAMLESS CONCRETE IPEFE BACKGROUND OF THEINVENTION 1. Field of the Invention This invention relates generally tothe art of pipe fabrication and more particularly to a novel method andmachine for extruding a cementitious material to form a continuousseamless pipe in a trench.

2. Discussion of the Prior Art Subsurface pipe lines are used for avariety of purposes, such as irrigation, sewage disposal, flood controland others. At the present time, such pipes are commonly constructed byexcavating a trench and placing within the trench precast concrete pipesections which are joined end to end to form a pipe. This method of pipeconstruction is quite time-consuming and costly and becomes more so asthe pipe diameter increases.

U.S. Pats. Nos. 2,731,698, 3,091,013 and 3,338,546 disclose an improvedmethod of subsurface concrete pipe construction. This constructionmethod involves the use of a pipe forming or extruding machine whichmoves forwardly through a trench and extrudes an annular ribbon ofconcrete or other cementitious mix to fonn a continuous seamless pipebehind the machine as the latter advances.

SUMMARY OF THE INVENTION The present invention provides an improved pipeforming machine of the general class described. The forming machine hasa carriage movable forwardly through the trench which is to contain thepipe. At the rear of the machine is a cylindrical drum having its axisparallel to the direction line of carriage movement and a diameter equalto the internal diameter of the pipe. Concentrically surrounding thedrum is a thin walled cylindrical skirt having a diameter approximatingthe outer diameter of the pipe. The drum and skirt define an interveningannular rearwardly opening cylinder about the drum.

Mounted on the carriage forwardly of the drum for reciprocating movementthrough the cylinder is an annular plunger. Actuator meanssuch ashydraulic ram means drive the plunger back and forth through thecylinder. Preferably, the plunger is divided into independently movablesegme'nts'power'ed by separate hydraulic cams. Between the plunger andthe drum is a reservoir for containing a cementitious mix which is fedto the reservoir through a hopper. On the rear end of the drum is arotary troweling device. The preferred cementitious mix is a semi-dryrelatively low slump concrete mix, such as medium aggregate, sand,cement and selected admixtures. The invention will be described inconnection with the use of such a concrete mix in the pipe formingmachine. As will appear from the later description, however, othercementitious mixes may be used in the machine consisting of any suitableaggregate and binder.

In operation, the pipe forming machine is propelled slowly through thetrench while it receives concrete mix through its hopper from a supplyvehicle which moves along the trench machine. The annular plunger of themachine is driven in a reciprocating stroke through the annular cylinderabout the machine drum. During each rearward stroke, the plungerdisplaces concrete mix from the reservoir into the cylinder as well asthrough openings in the skirt and finally extrudes the concrete throughthe rear open end of the cylinder to form a generally cylindrical pipewall. The plunger then retracts forwardly to effect entry of moreconcrete mix into the cylinder, after which the plunger is again drivenrearwardly through the cylinder to extrude an additional length of pipe.

The plunger is driven rearwardly with substantial force to extrude andcompact the concrete mix to form a virtually self-sustaining pipe wall.This force produces a forward reaction force on the machine carriagewhich aids in propelling the carriage forwardly through the trench. Anadditional propulsion means, such as a winch, is provided forsupplementing the reaction force produced by the plunger.

The drum of the machine supports the pipe wall internally as it isformed and smooths the inner wall surface as the drum moves forwardly.Additional smoothing of the inner wall surface, if necessary, may beaccomplished by the rotating trowel at the rear of the drum. A primaryfeature of the invention resides in the use of a low slump concrete mixin the present machine. This low slump concrete enables extrusion of aseamless concrete pipe without the necessity 'of supporting the pipeinternally until the concrete sets. According to another importantfeature of the invention, the drum, skirt and extrusion plunger mountvibrators for compacting the concrete mix as it is extruded so as toenhance the self-sustaining ability of the pipe wall.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. l is a top view of a pipe formingmachine according to the invention;

FIG. 2 is a longitudinal section through the machine;

FIG. 3 is a section taken on line 3-3 in FIG. 2;

FIG..4'is a section taken on line 44 in FIG. 2;

FIG. 5 is a section taken on line 5-5 in FIG. 2;

FIG. 6 is a side elevation of the shield of the machine; and

PEG. 7 is a section through a pipe extruded by the machine.

DESCRIITION OF THE PREFERRED EMBODIMENT The pipe forming machine 10selected for illustration in the drawings has a carriage 12 which ismovable forwardly in the direction of the arrow in FIG. 2 through atrench M. The trench has generally vertical side walls 116 and a roundedbottom wall 18. Machine carriage 112 has front and rear sections 20 and22 which can pivot laterally relative to one another,as explained below,to facilitate movement of the carriage around a curve.

Front carriage section 22 has a frame 24 with upstanding side walls 26and a rounded bottom wall 28, constructed of boiler plate of the like.The frame is shaped and dimensioned in transverse cross-section toconform approximately to the cross-section of the trench M. Mounted onthe bottom wall 23 is a platform 30 supporting a motor generator set orprime mover 32, in this instance an internal combustion engine. Engine32 drives a winch 36 through a transmission 33. As will be explainedpresently, the winch 36 is utilized to move the pipe forming machineforwardly through the trench M by attaching the winch cable 39 to ananchor located some distance ahead of the machine.

The rear carriage section 20 has a frame 50 constructed of boiler plateor the like in a manner similar to the front carriage section. The frontend of the rear section has a cross-section similar to that of the frontsection including a rounded bottom wall 42 and upstanding side walls 43.The remaining rear portion of the frame forms a cylindrical skirt 44whose bottom portion is a continuation of the bottom frame wall 42 andwhose axis coincides with the axis of curvature of the latter wall andthe bottom wall 28 of the front carriage section 22.

The front end of the rear carriage section fits within the rear end ofthe front carriage section 22 so as to overlap the latter section asmall amount. The front end of the rear section is sized to provide asmall clearance between the overlapping side walls 26, 43 of thesections. The overlapping bottom walls 28, 42 of the sections are joinedby a pivot 45. This pivot permits the two carriage sections to pivotlaterally relative to one another through a small angle such that thepipe forming machine may travel around curves in the trench 14. Thepivot is arranged to permit uncoupling of the two carriage sections forease of transportation from one job site to another.

Extending across the front end of the rear carriage section 20 andwelded or otherwise rigidly joined to the bottom and side frame walls42, 43 of the section are spaced parallel frame walls 46, 48. A hollowcylinder is welded or otherwise rigidly joined to the rear side of therear wall 48. Cylinder 50 has a cylindrical wall 52 and end walls 54,56. Mounted in the walls 46, 48, 54, 56 are shaft bearings 58. Cylinder50 and bearings 58 are aligned on the axis of the rear cylindrical skirt44 of the rear carriage section 20.

Rotatably supported in the bearings 58 is a hollow shaft 60. Shaft 60extends forwardly of the front frame wall 46 into the front carriagesection 22 and rear wardly of the rear cylinder end wall 56 through thecylindrical skirt 44 along the axis of the skirt. The front end of shaft60 is driven from the engine 32 through a speed reducer and clutchmechanism 62 and a belt or chain drive 64. Extending centrally throughand rotatably supported in the shaft 60 is an inner shaft 66. The frontend of shaft 66 is driven from the engine 32 through a speed reducer andclutch mechanism 68 and a belt or chain drive 70. It is significant tonote here that the belts or chains of the drives 64, 70 may be removedto permit uncoupling of the carriage sections 20, 22.

Fixed on the rear end of the outer shaft 60 is a hollow cylindrical drum72, the rear end of which projects a short distance beyond the rear endof the skirt 44. Drum 72 has a cylindrical wall 74, a somewhatdomeshaped front end wall 76 and a flatter rear end wall 78. As shownmost clearly in FIG. 2, the annular juncture 80 of the drum walls 74, 76is rounded. The annular juncture of the drum walls 74, 78 is alsorounded, though to a smaller radius. Cylinder 50 and drum 72 have thesame diameter which is the internal diameter of the pipe to be formed.Fixed on the rear end of the inner shaft 66 is a rotary trowel 81 of thesame diameter as the drum 72.

The skirt 44 of the rear carriage section 20 surrounds the cylinder 50and drum 72 concentrically and has a diameter approximating the outerpipe diameter. The skirt and cylinder define an intervening annularcylinder 82. The skirt and drum define an intervening annular cylinder84. Between the cylinder 50 and drum 72 is a space 86 providing areservoir. A hopper 88 rises from the top of the skirt 44 over thereservoir and opens downwardly to the reservoir. The front end of thedrum 72 mounts paddles 90 which project forwardly into the reservoir. Inthe sides of the skirt 44 are ports 92 which open to the reservoir. Therear end of the skirt is cut away at 94.

Movable through the annular cylinders 82, 84 is an annular plunger 96.This piston has an axial length approximating the length of the cylinder82. Actuator means 98, in this instance hydraulic or pneumatic rammeans, are connected to the plunger for moving the latter back and forththrough the cylinders. The plunger is movable between a forwardretracted position in the cylinder 82 and a rearward extended positionwithin the rear end of cylinder 84. During its movement between thesepositions, the plunger travels through the reservoir 86.

According to a feature of the invention the plunger 96 is divided intofour independently movable segments 96a. The actuator means 98 compriseseparate hydraulic rams 98a for driving the plunger segments back andforth. According to another feature of the invention, the drum 72, skirt44 and plunger 96 mount vibration generators 100 for vibrating theseparts.

Mounted atop the rear end of the skirt 44 is an operators station 101.This station is equipped with controls for engine 32, winch 36, clutchmechanisms 62, 68 and rams 98a.

In operation of the pipe forming machine, the winch cable 39 is anchoredsome distance ahead of the machine. The rams 98a are actuated to retractthe plunger 96. The reservoir 86 is filled with a semi-dry relativelylow slump concrete mix through the hopper 88. This concrete mix may besupplied to the machine by a concrete transport vehicle which movesalong the side of the trench with the pipe forming machine. A system ofbaffles which are apparent in FIG. 1 and FIG. 5 are placed in the hopperto direct more concrete mix to the sides of the reservoir rather thandown the center of the hopper. A major portion of the concrete thusfeeds to the ports 92 through which the concrete passes to the outrideof the skirt, and to the paddles 90. This action aids materially ingetting the concrete quickly and efficiently into the intervening spacebetween the outer skirt and the trench walls.

After the machine has been thus readied for operation, the winch 38 isoperated to wind the cable 39 on the winch drum and thereby advance themachine slowly through the trench 14. The drum 72 and trowel 81 aredriven in rotation. Rotation of the drum drives the drum paddles 90about the reservoir 86 to constantly mix and agitate the concrete mix inthe reservoir to prevent the mix from setting. This paddle rotation alsodisplaces concrete mix from the reservoir through the skirt ports 92into the region between the skirt 44 and the trench wall.

Actual extrusion of the concrete mix to form a pipe P is accomplished byoperating the rams 98a to reciprocate annular plunger 96 between itsretracted and extended positions. During each rearward stroke of theplunger, the latter displaces concrete mix from the reservoir 86outwardly through the skirt ports 92 into the region between the skirt44 and the trench wall and rearwardly through the cylinder 84 until theplunger enters over the rounded forward end of drum 72. As the plungerenters over the drum, the annular clearance space between the plungerand drum gradually closes by virtue of the rounded annular end wallportion 80 of the drum. As this clearance space closes, the plungercloses to displace concrete mix through the skirt ports 92 and continuesto displace concrete mix, under increased force or pressure, rearwardlythrough the cylinder 8d. The concrete mix is extruded through the rearopen end of the cylinder 84 to form the pipe P.

During this final portion of its extension or extrusion stroke, theplunger 96 imposes a relatively high force or pressure on the extrudingconcrete mix which compacts the mix. Additional compaction of theextruding concrete mix is accomplished by rotation of the drum 72 and bythe vibrating action of the vibration generators 100. This compaction ofthe mix coupled with its semi-dry low slump characteristics results inan extruded concrete pipe P which is self-supporting and eliminates theneed for internal supports within the pipe. In addition to extruding andcompacting the concrete mix, the high force exerted by the plungeragainst the extruded pipe wall produces an opposite reaction force onthe pipe forming machine. This reaction force aids the winch 36 inmoving the machine forwardly through the trench 114.

When the plunger 96 reaches the end of its rearward extrusion stroke, itis retracted to the forward end of its travel, after which the cycle isrepeated. Thus, the Pipe P is effectively extruded in successive butcontinuous sections during successive rearward extension strokes of theplunger. If necessary, the rate of forward travel of the machine throughthe trench 14 may be slowed or terminated during the forward'retract-ionor return strokes of the plunger to avoid the formation ofdiscontinuities or weak spots in the pipe wall.

A feature of the invention resides in the fact that the rotating drumpaddles 9:0 and annular plunger 96 cooperate to effect uniformdistribution of the concrete mix about the full circumference of theannular cylinder 34. The plunger segments 96a may be extended in unisonor independently, as required to obtain uniform extrusion of andpressure on the pipe wall about the full pipe circumference.

As the pipe forming machine advances, extruding the pipe P behind it,the inner pipe surface is smoothed by the rotating drum 72 and trowel81. In this regard, it should be noted that the drum may be driven inother than a rotary motion, such as an oscillating or reciprocatingmotion or, for that matter, the drum may remain stationary. If desirableor necessary, the machine may be equipped with means for spraying wateron the inner pipe surface to enhance this smoothing action.

A major advantage of the present pipe extruding machine resides in thefact that it produces a seamless pipe with a predetermined minimum wallthickness and a smooth walled bore having a high degree of roundness. Asnoted earlier, the preferred concrete mix for use in the machine is alow slump concrete which permits extrusion of a pipe without thenecessity of internally supporting the pipe wall until the concretesets. Other cementitious materials than concrete may be used, however.

What is claimed is:

l. A machine for forming a continuous seamless cementitious pipe withina trench, comprising:

a carriage movable forwardly through said trench,

a cylindrical drum at the rear of said carriage having its axis parallelto the direction line of carriage movement,

said drum having a diameter approximating the internal diameter of saidpipe and a cylindrical length which is a major portion of the overalllength of the drum means for driving said drum in a motion which doesnot alter the position of the drum axis relative to said carriage,

a cylindrical skirt about and concentric with said drum and having adiameter approximating the outer diameter of said pipe,

said drum and skirt defining an intervening rearwardly opening annularcylinder about the drum having a radial dimension approximating the wallthickness of said pipe,

means for feeding a cementitious mix into the forward end of saidcylinder, and

means for feeding said mix rearwardly through and extruding the mixthrough the rear end of said cylinder during said motion of said drum toform the pipe wall between the drum and the trench walls as the machinemoves forwardly through said trench, said feeding means comprisingannular plunger means movable axially through and having a radialdimension approximating that of said cylinder, and fluid power actuatormeans connected between said carriage and plunger means for driving saidplunger means back and forth through said cylinder.

2. A pipe forming machine according to claim 1 including:

vibrator means for vibrating said skirt.

3. A pipe forming machine according to claim 1 wherein:

said skirt has openings at the forward end of said drum through whichsaid cementitious mix may flow to the exterior of the skirt.

4. A pipe forming machine according to claim l wherein:

said plunger means comprises a number of independently movable segments,and

said actuator means comprises independent actuators for driving saidplunger segments independently through said cylinder.

5. A pipe forming machine according to claim 1 including:

paddles on the front end of said drum which rotates with said drum toagitate said mix entering the forward end of said cylinder anddistribute the mix uniformly about said cylinder.

6. A pipe forming machine according to claim 1 wherein:

said carriage includes a rear section mounting said drum, skirt, plungermeans and actuator means, and a front section,

means on said front section for driving said carriage through saidtrench, and

pivotal coupling means joining said carriage sections for relativelateral pivoting of said sections.

7. A pipe forming machine according to claim 6 wherein:

said coupling means are disengageable to permit separation of saidcarriage sections.

8. A pipe forming machine according to claim 11 including:

means for driving said drum in rotation,

a rotary trowel concentrically mounted at the rear end of and having thesame outer diameter as said drum, and

means for driving said trowel in rotation independently of said drummotion.

1. A machine for forming a continuous seamless cementitious pipe withina trench, comprising: a carriage movable forwardly through said trench,a cylindrical drum at the rear of said carriage having its axis parallelto the direction line of carriage movement, said drum having a diameterapproximating the internal diameter of said pipe and a cylindricallength which is a major portion of the overall length of the drum meansfor driving said drum in a motion which does not alter the position ofthe drum axis relative to said carriage, a cylindrical skirt about andconcentric with said drum and having a diameter approximating the outerdiameter of said pipe, said drum and skirt defining an interveningrearwardly opening annular cylinder about the drum having a radialdimension approximating the wall thickness of said pipe, means forfeeding a cementitious mix into the forward end of said cylinder, andmeans for feeding said mix rearwardly through and extruding the mixthrough the rear end of said cylinder during said motion of said drum toform the pipe wall between the drum and the trench walls as the machinemoves forwardly through said trench, said feeding means comprisingannular plunger means movable axially through and having a radialdimension approximating that of said cylinder, and fluid power actuatormeans connected between said carriage and plunger meaNs for driving saidplunger means back and forth through said cylinder.
 2. A pipe formingmachine according to claim 1 including: vibrator means for vibratingsaid skirt.
 3. A pipe forming machine according to claim 1 wherein: saidskirt has openings at the forward end of said drum through which saidcementitious mix may flow to the exterior of the skirt.
 4. A pipeforming machine according to claim 1 wherein: said plunger meanscomprises a number of independently movable segments, and said actuatormeans comprises independent actuators for driving said plunger segmentsindependently through said cylinder.
 5. A pipe forming machine accordingto claim 1 including: paddles on the front end of said drum whichrotates with said drum to agitate said mix entering the forward end ofsaid cylinder and distribute the mix uniformly about said cylinder.
 6. Apipe forming machine according to claim 1 wherein: said carriageincludes a rear section mounting said drum, skirt, plunger means andactuator means, and a front section, means on said front section fordriving said carriage through said trench, and pivotal coupling meansjoining said carriage sections for relative lateral pivoting of saidsections.
 7. A pipe forming machine according to claim 6 wherein: saidcoupling means are disengageable to permit separation of said carriagesections.
 8. A pipe forming machine according to claim 1 including:means for driving said drum in rotation, a rotary trowel concentricallymounted at the rear end of and having the same outer diameter as saiddrum, and means for driving said trowel in rotation independently ofsaid drum motion.